Vibration mitigation device

ABSTRACT

A vibration mitigation device configured to be fixedly coupled to a generally horizontally extending support member. The vibration mitigation device includes a generally vertically extending housing extending from the generally horizontally extending support member and a reciprocating assembly coupled with and fully enclosed inside of the generally vertically extending housing.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/878,016.

BACKGROUND OF THE DISCLOSURE

1. Technical Field of The Disclosure

The present invention is related in general to vibration mitigationsystems, and in particular to a vibration mitigation device thatincorporates a reciprocating assembly connected with a biasing member tomitigate vibration.

2. Description of The Related Art

Traffic signals are used extensively all over the world to controlconflicting flows of traffic. The traffic signals are attached to talltraffic signal poles and horizontally extending mast arms or cables toensure clear visibility of traffic signals for the drivers orpedestrians. Various types of signal support structures are currentlyemployed, of which cantilevered support structures are widely used astraffic signal support structures since they consist of less materialwith only one vertical pole. However, cantilevered structures areflexible, lightly-damped structures that are highly susceptible towind-induced vibration. The sustained large amplitude deflections due toexcessive wind-induced vibrations can result in fatigue failure of themast arm and vertical pole connection. This fatigue failure willultimately lead to failure of these structures and represents asignificant cost to signal owners.

Reducing the effective stress range in the structure by reducing theamplitude of the vibration can significantly increase the life of thatstructure. This can be done by increasing the damping of the structurewith an effective damping device that would decrease the amplitude andnumber of cycles, thus extending the service life of the structure. Anumber of different methods have been suggested to increase the dampingof the structure and reduce the excessive wind induced vibration oftraffic poles. One such method employs a Signal Head Vibration Absorber(SHVA), which is a promising type of vibration absorber for trafficsignal support structures. This device has been experimentally shown toincrease the critical damping ratio of the traffic signal structuresfrom less than 1% to over 10%, virtually eliminating any vibration, andprotecting the structure from fatigue damage.

In a known prior art related to the vibration dampening systems, thedamping assembly employs multiple doughnut shaped metal discs or weightsvertically and loosely arranged in a unique fashion about a rod,disposed in a housing within the pole to reduce vibrations. However, thedamper requires larger diameter poles which in turn would result in anover-sized support structure. Additionally, this class of damper, basedon friction and/or impact damping, is amplitude dependent and may not beeffective over certain ranges of vibration amplitudes.

Recent advancements in the art provide a vibration absorber, the SHVAnoted above, for traffic signal supports. The SHVA utilizes the mass ofthe signal head in a configuration as a damped vibration absorber. Thesystem also includes a spring and damper in mechanical communicationwith the signal head. However, the downside to this system is that theabsorber requires utilization of the mass of the traffic signal whichitself plays a critical function and the SHVA unit contains componentsexposed to the elements which requires regular maintenance.

Based on the foregoing there is a need for a vibration mitigation devicewhich utilizes viscous or velocity dependent damping for energydissipation, eliminates the utilization of the mass of the trafficsignal and is self-contained with all critical components protected fromthe elements. Such a needed device would comprise a reciprocatingassembly connected to a biasing member. The device would utilize atension spring or a compression spring in an eddy current dampeningprocess and/or a pneumatic process to dissipate energy and reducevibrations. The present invention overcomes prior art shortcomings byaccomplishing these critical objectives.

SUMMARY OF THE DISCLOSURE

To minimize the limitations found in the prior art, and to minimizeother limitations that will be apparent upon the reading of thespecification, the preferred embodiment of the present inventionprovides a vibration mitigation device which uses viscous or velocitydependent damping to dissipate energy, eliminates the utilization of themass of the traffic signal and is self-contained with all criticalcomponents protected from the elements.

The present invention discloses a vibration mitigation device configuredto be fixedly coupled to a generally horizontally extending supportmember. The vibration mitigation device includes a generally verticallyextending housing extending from the generally horizontally extendingsupport member and a reciprocating assembly coupled with and fullyenclosed inside of the generally vertically extending housing. Accordingto a first preferred embodiment, the reciprocating assembly includes apair of opposing conducting rods disposed along a longitudinal path withrespect to the generally vertically extending housing, a mass fixedlyconnected with a plurality of magnets arranged to provide a magneticfield across the pair of opposing conducting rods and configured totranslate along the vertical path with respect to the generallyvertically extending housing, a plurality of securing guides coupledwith the mass and configured to allow the mass to reciprocate relativeto the conducting rods and the vertically extending housing, and abiasing member configured to couple the reciprocating assembly with thegenerally vertically extending housing and configured to support theplurality of magnets and the mass in a neutral position with respect tothe generally vertically extending housing when the vibration mitigationdevice is at rest. According to an alternative embodiment, the entiretyor a portion of the housing itself may be used as the conductingmaterial and the conducting rods may be eliminated.

In accordance with one embodiment of the present invention, thevibration mitigation device utilizes a tension spring as the biasingmember in an eddy current dampening process. In this embodiment, thevibration mitigation device functions as an eddy current dampeningdevice by generating eddy current when the conducting material is movedwithin the magnetic field of the device. In this embodiment, theconducting material is preferably disposed along the longitudinal pathtravelled by the mass and the plurality of magnets. Preferably, the pairof opposing conducting rods is configured with the plurality of magnetsin such a way that the plurality of magnets move up and down relative tothe pair of opposing conducting rods. In this configuration, theplurality of magnets dissipates the energy in the vibration mitigationdevice, resulting in motion dampening of the vibrating system.

In accordance with another exemplary embodiment of the presentinvention, the vibration mitigation device utilizes a tension spring asthe biasing member in a pneumatic process. In this configuration, thevibration mitigation device includes a sealed outer case, an upper airchamber, the tension spring, a mass and a lower air chamber. The massincludes a pair of bushings that provides a contact surface for guidingthe mass by the sealed outer case. The sealed outer case ispneumatically sealed and the mass is suspended by the tension spring andreciprocates vertically along the upper air chamber and the lower airchamber. During excessive vibrations in the support structure, the massmoves up and down in the sealed outer case, resulting in the exchange ofair from one side of the mass to the other. This creates a suction orairflow resistance in the upper air chamber or lower air chamber, whichslows the mass and dampens the vibration. In one embodiment, the massincludes side and/or interior relief conduits that allow air tocommunicate between the upper air chamber and the lower air chamber.

In accordance with yet another exemplary embodiment of the presentinvention, the vibration mitigation device utilizes a tension spring asthe biasing member while operating in both the pneumatic process and theeddy current dampening process. This hybrid embodiment may work betterover a wide spectrum of vibration amplitudes. For low amplitude, theeddy current dampening process may provide improved vibration mitigationresults and for higher amplitudes, the pneumatic process may provideimproved vibration mitigation results. Other exemplary embodimentsprovide a vibration damping element that utilizes a compression springas a biasing member for mitigating vibrations. Further exemplaryembodiments provide a vibration damping element that utilizes acompression spring and a tension spring as biasing members formitigating vibrations.

These and other advantages and features of the present invention aredescribed with specificity so as to make the present inventionunderstandable to one of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Elements in the figures have not necessarily been drawn to scale inorder to enhance their clarity and improve understanding of thesevarious elements and embodiments of the invention. Furthermore, elementsthat are known to be common and well understood to those in the industryare not depicted in order to provide a clear view of the variousembodiments of the invention, thus the drawings are generalized in formin the interest of clarity and conciseness.

FIG. 1 is a perspective view of a preferred embodiment of a vibrationmitigation device of the present invention;

FIG. 2 is an enlarged view of a reciprocating assembly incorporatedwithin the vibration mitigation device of the present invention;

FIG. 3 is a partially cut-away schematic diagram of an exemplaryvibration mitigation device of one embodiment of the present invention;and

FIG. 4 is a schematic diagram of the vibration mitigation device shownin FIG. 3, illustrating flow of air between an upper air chamber and alower air chamber.

FIG. 5 is a perspective view of a preferred alternative embodiment of avibration mitigation device of the present invention;

FIG. 6 is an enlarged view of a reciprocating assembly incorporatedwithin a preferred alternative embodiment of a vibration mitigationdevice of the present invention; and

FIG. 7 is a schematic diagram of the vibration mitigation device shownin FIG. 6, illustrating flow of air between an upper air chamber and alower air chamber.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following discussion that addresses a number of embodiments andapplications of the present invention, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand changes may be made without departing from the scope of the presentinvention.

Various inventive features are described below that can each be usedindependently of one another or in combination with other features.However, any single inventive feature may not address any of theproblems discussed above or only address one of the problems discussedabove. Further, one or more of the problems discussed above may not befully addressed by any of the features described below.

FIG. 1 is a perspective view of a preferred embodiment of a vibrationmitigation device 100 of the present invention. The vibration mitigationdevice 100 is configured to be fixedly coupled to a generallyhorizontally extending support member (not shown). The device 100includes a generally vertically extending housing 112 with a second endcap 102, a first end cap 108, a pair of opposing conducting rods 126disposed along a vertical path with respect to the generally verticallyextending housing 112 and a reciprocating assembly 114 reciprocatinglycoupled with the generally vertically extending housing 112.

The reciprocating assembly 114 as shown preferably includes a mass 118and a plurality of magnets 116 connected to the mass 118. The magnets116 are preferable configured to translate along a vertical path withrespect to the generally vertically extending housing 112 and to therebyprovide a magnetic field across the conducting rods 126. As shown, thereciprocating assembly preferably further includes a plurality of guides124 coupled with the mass 118 by at least one fastening element 120 andconfigured to allow the mass 118 to translate reciprocatingly by thepair of opposing conducting rods 126. As further shown, the verticallyextending housing 112 and a biasing member 122 are coupled to thereciprocating assembly 114. The vertically extending housing 112includes a first end cap 108 which connects to the biasing member 122via a connecting element 128. Preferably, the biasing member 122 isconfigured to support the plurality of magnets 116 and the mass 118 in aneutral position with respect to the generally vertically extendinghousing 112 when the vibration mitigation device 100 is at rest. Thebiasing member 122 includes at least one tension spring or a compressionspring. The end caps 102 and 108 are preferably of unitary construction.

With reference now to FIG. 2, an enlarged view of the reciprocatingassembly 114 incorporated within the vibration mitigation device 100 ofthe present invention is illustrated. In one embodiment, the vibrationmitigation device 100 utilizes a tension spring as the biasing member122 in an eddy current dampening process. In this embodiment, thevibration mitigation device 100 functions as an eddy current dampeningdevice by generating eddy current when the pair of opposing conductingrods 126 is moved within the magnetic field of the device 100. At rest,the mass 118 is suspended on the biasing member 122 within the generallyvertically extending housing 112. When vibrational force is applied, themass 118 reciprocates up and down within the generally verticallyextending housing 112.

According to a further aspect of the first preferred embodiment, thepair of opposing conducting rods 126 are preferably formed of conductingmaterial and placed along the vertical path travelled by the mass 118and the plurality of magnets 116. Preferably, the pair of opposingconducting rods 126 are secured within the vertically extending housing112 in such a way that the plurality of magnets 116 moves up and downrelative to and provides a magnetic field across the pair of opposingconducting rods 126. In this process, the plurality of magnets 116create eddy currents in the conducting material which dissipates theenergy of the vibration mitigation device 100, resulting in motiondampening of the support member. The conducting material of conductingrods 126 may preferably be formed from any non-ferrous metal(s). Forexample, in one embodiment, the conducting material may includealuminum, copper, gold, silver or a combination thereof. The pluralityof magnets 116 may include a permanent magnetic material, aferromagnetic material, a ferromagnetic material or an electromagnet.The plurality of guides 124 are preferably coupled with the mass 118 byat least one fastening element 120.

In one embodiment, the eddy current dampening device generateselectricity, which is sufficient to run an LED light.

In an alternative exemplary embodiment of the present invention, asshown in FIGS. 3 and 4, a vibration mitigation device 200 utilizes atension spring 208 as the biasing member in a pneumatic process. Thevibration mitigation device 200 includes a sealed outer case 202, anupper air chamber 204, a tension spring 208, a mass 210 and a lower airchamber 206. The mass 210 includes a pair of bushings 212 that provide acontact surface for guiding the mass 210 within the sealed outer case202. In one embodiment, the mass 210 includes a plurality of stackedweights that are stacked together by at least one fastening element 214.The at least one fastening element 214 may include nuts and bolts.

The sealed outer case 202 is preferably pneumatically sealed and themass 210 is suspended by the tension spring 208 and allowed toreciprocate vertically. During excessive vibrations in the supportstructures, the mass 210 is preferably configured to move up and down inthe sealed outer case 202 resulting in exchange of air from one side ofthe mass 210 to the other. This creates a suction or airflow resistancein the upper air chamber 204 or lower air chamber 206 to slow the mass210 and dampen the vibration. In one embodiment, the mass 210 includesside and/or interior relief conduits that allow air to communicatebetween the upper air chamber 204 and the lower air chamber 206.

FIG. 4 is a schematic diagram of the vibration mitigation device 200shown in FIG. 3, illustrating a flow of air between the upper airchamber 204 and the lower air chamber 206. As shown, the motion of themass 210 suspended by the tension spring 208 is excited through themotion of the mass arm that the device 200 is attached to and isindicated by the arrow 216. As further shown in FIG. 4, as the mass 210travels up and down inside the sealed outer case 202, the volume of airbetween the upper air chamber 204 and the lower air chamber 206 changes.Specifically, as the mass 210 strokes downward, volume of the lower airchamber 206 decreases and the upper air chamber 204 increases. As volumeof the lower air chamber 206 decreases, pressure increases, causing aresistance resulting in an upward damping force on the mass 210.Conversely, as the mass 210 strokes upward, the volume in the lower airchamber 206 increases and the volume of the upper air chamber 204decreases. When the volume of the lower air chamber 206 increases, thepressure decreases, resulting in a damping force opposing the motion ofthe mass 210. The exchange of volume between the upper air chamber 204and the lower air chamber 206 is indicated by the arrow 218. The amountof air exchanged may be adjusted by various elements including but notlimited to: orifice plates drilled through the mass, valves and internalclearances.

FIG. 5 is a perspective view of a preferred alternative embodiment of avibration mitigation device 500 of the present invention. As shown, thevibration mitigation device 500 includes a generally verticallyextending housing 502, a reciprocating assembly 510 arranged forreciprocating movement within the housing 502 and spring 508. Accordingto a preferred embodiment, the spring 508 may be a tension spring, acompression spring or the like.

With reference now to FIGS. 6 and 7, a detailed explanation of analternative preferred embodiment as shown in FIG. 5 shall now bediscussed. As shown in FIG. 6, a cut-way view is provided illustratingthe interiors of the vertical housing assembly 602 (referred to as 502in FIG. 5) and the reciprocating assembly 610 (referred to as 510 inFIG. 5). As shown, the vibration mitigation device 600 may preferablyinclude a tension spring 608 as the biasing member in a pneumaticprocess, with the tension spring 608 attached to reciprocating massassembly 610. As further shown, the reciprocating assembly 610 may beconstructed as a cast iron weight 614 sealed within the reciprocatingassembly 610 and may further include an upper slide bearing 612 and alower slide bearing 613 to guide the movement of the reciprocatingassembly 610. To assist and control air flow within the vertical housingassembly 602, the reciprocating assembly 610 may further include upperpneumatic air passages 622 and lower pneumatic air passages 618.Additionally, the reciprocating assembly 610 as shown may preferablyfurther include a cushioning element 616 as well as a magnet element620. According to a further preferred embodiment, magnet element 620 maybe a rare earth magnet and cushioning element 616 may be a rubber bumperor the like.

FIG. 7 is a schematic diagram of the vibration mitigation device shownin FIG. 6. As shown, FIG. 7 illustrates the flow of air between theupper pneumatic air passages 724 and the lower pneumatic air passages726. As discussed above with respect to other embodiments, the motion ofthe reciprocating assembly 710 suspended by the tension spring 708 isexcited through the motion of the mass arm that the device 700 isattached to (not shown). As discussed above, in response to vibrationalforces, the reciprocating assembly 710 travels up and down inside thesealed outer case 702 which results in a change in volume between theupper air chamber 704 and the lower air chamber 706. Specifically, asthe reciprocating assembly 710 strokes downward, the volume of the lowerair chamber 706 decreases and the volume the upper air chamber 704increases. As the air volume of the lower air chamber 706 decreases, thepressure increases, causing a resistance resulting in an upward dampingforce on the reciprocating assembly 710. Conversely, as thereciprocating assembly 710 strokes upward, the volume of the lower airchamber 706 increases and the volume of upper air chamber 704 decreases.When the volume of the lower air chamber 706 increases, the pressuredecreases, resulting in a damping force opposing the motion of thereciprocating assembly 710.

As detailed in FIG. 7, according to an alternative preferred embodiment,the exchange of volume between the upper air chamber 704 and the lowerair chamber 706 is preferably directed through the upper pneumatic airpassages 724 and the lower pneumatic air passages 726 as indicated bythe arrow 728. The amount of air exchanged may be adjusted by variouselements including but not limited to: orifice plates drilled throughthe mass, valves and internal clearances.

As further shown in FIG. 7, the reciprocating assembly 710 preferablyfurther includes a magnet element 720. As discussed above, magnetelement 720 preferably creates eddy currents in surrounding conductingmaterials which dissipates the energy of the vibration mitigation device700, resulting in motion dampening. Preferably, magnet element 720 iscomprised of a rare earth magnet. Alternatively, magnet element 720 maybe formed of any permanent magnetic material, ferromagnetic material,ferromagnetic material or an electromagnet.

According to a further aspect of the present invention, the conductivematerials of the present invention may be incorporated into thestructure of the sealed outer case 702. According to a preferredembodiment, the sealed outer case 702 may be lined with conductivematerial. Alternatively, the conductive material may be incorporatedinto the entirety of the wall structure of the sealed outer case 702 oronly embedded within discrete section(s) of the sealed outer case 702.

In another exemplary embodiment of the present invention, a tensionspring is utilized as the biasing member when the vibration mitigationdevice operates in both the pneumatic process and the eddy currentdampening process as described above. This hybrid embodiment may workbetter over a wide spectrum of vibration amplitudes. For low amplitudes,the eddy current dampening process may provide improved vibrationmitigation results and for higher amplitudes, the pneumatic process mayprovide improved vibration mitigation results. Other exemplaryembodiments provide a vibration damping element that utilizes acompression spring as a biasing member for mitigating vibrations.Further exemplary embodiments provide a vibration damping element thatutilizes a compression spring and a tension spring as biasing membersfor mitigating vibrations.

According to a further preferred embodiment, the present invention mayuse a hydraulic or other liquid based pressure source in place of thepneumatic (air) pressure source discussed above. Accordingly, hydraulicfluid, oil, water or another liquid may be used within the vibrationdampening element to allow for pressure adjustments between the upperand lower chambers of the vertically extending housing as discussedabove.

In one embodiment, the present invention includes a vibration mitigationdevice that can be configured to reduce naturally induced vibrations andattached to a variety of support structures including at least one of abridged structure, a cantilever or a multi-pole support system holdingor supporting lighting, traffic signals, street signs, signage, camerasor other devices.

The foregoing description of the preferred embodiment of the presentinvention has been presented for the purpose of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Many modifications andvariations are possible in light of the above teachings. It is intendedthat the scope of the present invention not be limited by this detaileddescription, but by the claims and the equivalents to the claimsappended hereto.

We claim:
 1. A vibration mitigation apparatus, wherein the vibrationmitigation apparatus comprises: a vertically extending housing, whereinthe vertically extending housing comprises: a first end cap; a secondend cap; and a centrally enclosed area; a reciprocating assembly,wherein the reciprocating assembly is enclosed within the verticallyextending housing and configured to move vertically within thevertically extending housing, wherein the reciprocating assembly furthercomprises a plurality of air passages to allow air to transfer betweenthe spaces above and below the reciprocating assembly; and a biasingmember, wherein the biasing member is attached to the verticallyextending housing and to the reciprocating assembly, wherein the biasingmember is configured to support the mass in a neutral position withrespect to the vertically extending housing when the vibrationmitigation apparatus is at rest.
 2. The apparatus of claim 1, whereinthe reciprocating assembly comprises upper air passages and lower airpassages.
 3. The apparatus of claim 2, wherein the reciprocatingassembly comprises one or more weight elements which are configured toincrease the weight of the reciprocating assembly.
 4. The apparatus ofclaim 3, wherein the biasing element is comprised of a tension spring.5. The apparatus of claim 4, wherein the biasing element is comprised ofa compression spring.
 6. A vibration mitigation apparatus, wherein thevibration mitigation apparatus comprises: a vertically extendinghousing, wherein the vertically extending housing comprises: a first endcap; a second end cap; and a centrally enclosed area; a reciprocatingassembly, wherein the reciprocating assembly is enclosed within thevertically extending housing and configured to move vertically withinthe vertically extending housing, wherein the reciprocating assemblyfurther; and a magnetic element, wherein the magnetic element isattached to the reciprocating assembly and further wherein the magneticelement is configured to produce eddy currents as the reciprocatingassembly moves vertically within the vertically extended housing.
 7. Theapparatus of claim 6 wherein the apparatus further comprises aconducting element.
 8. The apparatus of claim 7, wherein the verticallyextending housing further comprises at least one portion of the housingwhich is comprised of a conducting material.
 9. The apparatus of claim7, wherein the conducted element comprises a conducting rod.
 11. Theapparatus of claim 9, wherein the magnet element is comprised of a rareearth magnet.
 12. A vibration mitigation apparatus, wherein thevibration mitigation apparatus comprises: a vertically extendinghousing, wherein the vertically extending housing comprises: a first endcap; a second end cap; and a centrally enclosed area; a reciprocatingassembly, wherein the reciprocating assembly is enclosed within thevertically extending housing and configured to move vertically withinthe vertically extending housing, wherein the reciprocating assemblyfurther comprises a plurality of air passages to allow air to transferbetween the spaces above and below the reciprocating assembly; a biasingmember, wherein the biasing member is attached to the verticallyextending housing and to the reciprocating assembly, wherein the biasingmember is configured to support the mass in a neutral position withrespect to the vertically extending housing when the vibrationmitigation apparatus is at rest; and a magnetic element, wherein themagnetic element is attached to the reciprocating assembly and furtherwherein the magnetic element is configured to produce eddy currents asthe reciprocating assembly moves vertically within the verticallyextended housing.
 13. The apparatus of claim 12, wherein the apparatusfurther comprises a conducting element.
 14. The apparatus of claim 13,wherein the vertically extending housing further comprises at least oneportion of the housing which is comprised of a conducting material. 15.The apparatus of claim 14, wherein the reciprocating assembly comprisesupper air passages and lower air passages.
 16. The apparatus of claim13, wherein the conducted element comprises a conducting rod.
 17. Theapparatus of claim 16, wherein the magnet element is comprised of a rareearth magnet.
 18. The apparatus of claim 17, wherein the reciprocatingassembly comprises one or more weight elements which are configured toincrease the weight of the reciprocating assembly.
 19. The apparatus ofclaim 18, wherein the biasing element is comprised of a tension spring.20. The apparatus of claim 18, wherein the biasing element is comprisedof a compression spring.